It is a known practice in the printing of small-format printing sheets to use printing units in which the cylinders participating in the printing, such as a plate cylinder, a rubber or blanket cylinder and a printing cylinder, have different diameters. Through the use of cylinders of different diameters it is possible to save material costs with regard to the printing plates, the rubber blankets or the printing cylinder.
A sheet-fed rotary printing machine is disclosed in DE-PS 24 35 203. This printing machine includes in its most diverse configurations plate cylinders with a single or simple diameter, a rubber cylinder with a multiple diameter and a printing cylinder with a single diameter. With this arrangement, a partial portion of a print image can be printed on one of several segments of the rubber cylinder from differently installable printing units of a particular plate cylinder. Simultaneously, this print image can be printed on a printing sheet led on the printing cylinder. In such a system, the printing sheet revolves with the printing cylinder in correspondence to the movement of the segments of the rubber cylinder and is thereby printed.
In U.S. Pat. No. 3,347,160 there is described an ink roller device for a multicolor rotary offset printing machine. The printing machine disclosed in this reference includes a plate cylinder and a rubber cylinder, each having a multiple diameter, to which there is allocated a printing cylinder having a single or simple diameter. In the printing operation, the print image consists of several image parts that are generated on the plate cylinder of several cycled inking and moistening units, the image parts are transferred to the large, multiple-sized rubber cylinder and printed on a printing sheet guided on the printing cylinder. The printing cylinder revolves multiple times in correspondence to the diameter ratio between the rubber cylinder and the printing cylinder, until all of the print image parts are transferred to the printing sheet. This multicolor printing machine is particularly suited for so-called proof printing. The problem with these devices is that while they can be arranged as individual printing units, the costs associated with printing with images that contain more ink than permitted by the particular printing machine are very high. Accordingly, these printing machines are suited only for special printing processes.